“The first thing to do is to decide what more sustainability actually means in connection with microchips,” explains Tobias Berndt, Sustainability Project Manager in ZEISS’ Semiconductor Manufacturing Technology segment, “An entire range of machines and processes are needed for manufacturing microchips. Optical lithography systems have a very important role in them, and we develop and produce these systems in the ZEISS Semiconductor Manufacturing Technology segment. To make them more sustainable, we look primarily at the product development and manufacturing process for the optical systems and the infrastructure needed for it. On top of that, our products are also influenced by the attributes of the chips that they are used to make.”
Optical lithography is the key process used for manufacturing microchips. It involves a round disk consisting of silicon wafer with a photoresist coating being used as a foundation for the microchips and a pattern of an optical mask being greatly reduced in size and transferred onto the foundation using various chemical and physical processes. The electronic components and traces on the microchips are created by repeating these processes about 100 times.
ZEISS, working together with its strategic partner ASML and a large network, has brought this technology to the next level through a development process that has lasted over 20 years. The result? EUV lithography (EUV = extreme ultraviolet).
EUV projection optics are capable of high resolutions, which lets them manufacture very fine structures that allow for many transistors (miniature electrical switches) to be put on the microchips. Processors become more powerful as the number of transistors per chip grows. The development has been progressing for over half a century, with a phenomenon known as Moore’s law (named after Intel cofounder Gordon Moore) claiming that the number of transistors on a microchip doubles every two years. ZEISS and its partners have also had a hand in this progress.
What impact does higher performance have on sustainability? “EUV chips are, among other things, roughly 30 percent more energy-efficient than chips made using the most recent generation of deep ultraviolet (DUV) optics. This makes it possible to build significantly better-performing devices without enlarging their carbon footprint,” says Birgit Kürz, who works in product development and is a member of the Sustainability Team.
Product development has a fundamental role in the optimization of lithography systems, in terms of performance as well as sustainability.
“The most important thing is to get a clear idea of the consumption and emissions that production causes, and that means measuring key performance indicators. You cannot improve things if they are not measured,” adds Ingo Hofmann, Project Manager and a member of the Sustainability Team at ZEISS Semiconductor Manufacturing Technology, “We are currently building up our foundational data. When it comes to sustainability, we study what impacts we have on the environment right from the product development stage. After we do this, we can ask ourselves, ‘How can we reduce these impacts?’”
This process has already produced helpful findings. “Energy is the biggest lever at our disposal because our processes and production operations have such high demands.” What he is referring to here are clean rooms, the spaces in which ZEISS manufactures the lenses and mirrors for lithography optics. The requirements for air purity are very strict. “Our energy consumption is high because we need heavily air-conditioned clean rooms. Nonetheless, we are constantly optimizing our infrastructure.” For example, consumed energy is reused smartly and process waste heat is reclaimed in heating systems. “Microchips are used for this as well,” says Ingo Hofmann,
“They are a basis for intelligent switches that we can use to optimize our production halls.” His team questions everything: Does the machinery need to be in the clean room, or would a less energy-consuming area suffice too? The latter can reduce the area needed for clean rooms, which in turn has a positive influence on energy consumption. This is something that ZEISS looks at closely when moving into newly constructed buildings. It is also just as important that employee awareness is raised. “Which processes can we improve? How can we stop machines from being on standby for an unnecessarily long time? The ZEISS mindset is known to be about efficiency and precision, and our aim is to refine this mindset in relation to sustainability, too,” says Ingo Hofmann. There are also initiatives that can be taken for resource consumption. “We are currently looking at using ‘green steel.’ Manufacturing steel consumes a great amount of electricity, so it is usually associated with significant carbon emissions. If the electricity used for it is generated from renewable sources, this process can be completed in a considerably more sustainable way,” says Tobias Berndt. However, on a critical note, he adds, “There is always a question you need to ask: How was this electricity made ‘green’? Through carbon offset certificates – which generally are OK – or by actually using renewable energies with power purchase agreements (PPAs)? The latter is even better because in that case there is never even any carbon dioxide produced that you would have to offset later on. This is something we are investigating right now.”
“Investigating” is a fitting choice of word, as Tobias Berndt and his team are currently working on a comprehensive program for establishing sustainability within ZEISS Semiconductor Manufacturing Technology and for approaching the topic strategically. They use nine core questions to align themselves with the Group’s targets and initiate projects to achieve the targets. The team is constantly on the lookout for new, promising ideas for projects. Tobias Berndt says optimistically, “As a manufacturing company, we are aware of our responsibility for sustainability, and this awareness is growing among customers and suppliers, too.”
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